Most vertical takeoff and landing vehicles rely on gyro stabilization systems to remain stable in hovering flight. For instance, the inventor's previous U.S. Pat. No. 5,971,320 and corresponding International PCT Application WO 99/10235 disclose a helicopter with a gyroscopic rotor assembly to control the orientation or yaw of the helicopter. However, different characteristics are present when the entire body of the vehicle, such as a flying saucer, rotates. Gyro stabilization systems are typically no longer useful when the entire body rotates, for example, see U.S. Pat. Nos. 5,297,759; 5,634,839; 5,672,086; and U.S. Pat. Nos. 6,843,699 and 6,899,586.
However, a great deal of effort is still made in the prior art to eliminate or counteract the torque created by horizontal rotating propellers in flying aircraft in an effort to increase stability. For example, Japanese Patent Application Number 63-026355 to Keyence Corp. provides a first pair of horizontal propellers reversely rotating from a second pair of horizontal propellers in order to eliminate torque. See also U.S. Pat. No. 5,071,383 which incorporates two horizontal propellers rotating in opposite directions to eliminate rotation of the aircraft. Similarly, U.S. Pat. No. 3,568,358 discloses means for providing a counter-torque to the torque produced by a propeller because, as stated in the '358 patent, torque creates instability as well as reducing the propeller speed and effective efficiency of the propeller.
The prior art also includes flying or rotary aircraft which have disclosed the ability to stabilize the aircraft without the need for counter-rotating propellers. U.S. Pat. No. 5,297,759 incorporates a plurality of blades positioned around a hub and its central axis and fixed in pitch. A pair of rotors pitched transversely to a central axis to provide lift and rotation are mounted on diametrically opposing blades. Each blade includes down-turned outer tips, which create a passive stability by generating transverse lift forces to counteract imbalance of vertical lift forces generated by the blades. This helps to maintain the center of lift on the central axis of the rotors. In addition, because the rotors are pitched transversely to the central axis to provide lift and rotation, the lift generated by the blades is always greater than the lift generated by the rotors.
Nevertheless, there is always a continual need to provide new and novel self-stabilizing rotating vehicles that do not rely on additional rotors to counter the torque of a main rotor. Such self-stabilizing rotating vehicles should be inexpensive and relatively noncomplex.
In addition to providing a self-stabilizing rotating vehicle, the ability to provide a simple hovering vehicle that is also controllable greatly enhances the vehicle. When the entire vehicle rotates the vehicle loses an orientation reference, which helps the remote user determine the direction in which the vehicle should move. In helicopters, airplanes, or other typical flying aircraft that have defined front ends or noses, the aircraft has a specific orientation that is predetermined by the nose of the vehicle. In such circumstances a user controlling the aircraft could push a joystick controller forwards (or push a forwards button) to direct the aircraft to travel forwards from its point of reference; similar directional controls are found in conventional remote controlled vehicles. However, when a vehicle completely rotates, such as a flying saucer or any other rotating vehicle, the rotating vehicle loses its orientation as soon as it begins to spin, making directional control difficult to implement. For example, U.S. Pat. No. 5,429,542 to Britt Jr. as well as U.S. Pat. No. 5,297,759 to Tilbor et al. disclose rotating vehicles but only address movement in an upwards, downwards, and spinning direction; and U.S. Pat. Nos. 5,634,839 and 5,672,086 to Dixon discuss the use of a control signal to direct the rotating vehicle towards or away from the user, thus requiring the user to move about the rotating vehicle to the left or right if the user wants the rotating vehicle to move towards that particular direction.
Furthermore, U.S. Pat. No. 5,259,729 assigned to Keyence Corporation attempted to provide a propeller blade tip path plane inclination device to help control the direction of the vehicle during flight. While this provides a good solution, U.S. Pat. No. 5,259,729 has difficulties. In certain circumstances, movement of the tip plane is undesirable. For example, when the propeller is placed within a circular outer hub with very little top and/or bottom clearance, movement of the tip plane should be prevented to avoid having the tip make contact with other parts of the vehicle. In addition, when the propeller is part of a stacked propeller design inclination must be avoided to prevent the propellers from touching during flight. Embodiments provided herein attempt to solve these difficulties.